Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 282345
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
645 PM CDT SAT MAR 28 2015

.SYNOPSIS...
ISSUED AT 314 PM CDT SAT MAR 28 2015

REMARKABLY COLD HIGH PRESSURE IS FOUND OVER THE GREAT LAKES REGION
TODAY...WITH EASTERN IOWA AND NORTHWEST ILLINOIS CLOSE ENOUGH TO THE
CENTER TO HAVE LIGHT WINDS...FROM THE SOUTH AND SOUTHEAST. THIS
LIGHT WIND AND SUN HAVE SHOWN THAT WE HAVE MIXED DEEP ENOUGH TO
ALLOW FOR A 20 DEGREE DIURNAL RISE THROUGH 1 PM...WITH MOST SITES
LIKELY TO EXCEED 40 THIS AFTERNOON BEFORE ALL SAID AND DONE. ODDLY
ENOUGH...IT IS RATHER LIKELY THAT TODAY IS THE MORE PLEASANT DAY OF
THE WEEKEND...DESPITE SUNDAYS MILDER TEMPERATURES.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 314 PM CDT SAT MAR 28 2015

WARM ADVECTION WILL DOMINATE THE NEXT 24 HOURS...WITH TEMPERATURES
CLIMBING FROM WINTER LIKE READINGS...BACK TO SPRING BEFORE ITS DONE.
TONIGHTS LOW WILL DEFINITELY OCCUR BETWEEN 9 PM AND 3 AM...AS WINDS
ARE LIGHTEST UNDER CLEAR SKIES...AFTER WHICH...RISING TEMPERATURES
INTO THE LOWER TO MID 30S IS EXPECTED AS CLOUDS INCREASE...AS DO
WINDS. THE LIMITING FACTOR TO RAINFALL SUNDAY MORNING WILL BE
MOISTURE...THE FORCING REMAINS GOOD...AND WITH MODEST INSTABILITY
ALOFT...THE RAIN SHOULD BE SHOWERY IN NATURE. ALL MESOSCALE GUIDANCE
SUGGEST SHOWERS WILL INCREASE IN COVERAGE AS THEY MOVE FROM WEST TO
EAST THROUGH OUR CWA...AND WILL MAINTAIN THIS IN OUR POPS.
HOWEVER...GIVEN THE CONVECTIVE NATURE OF THE FORECAST...CATEGORICAL
POPS ARE FREQUENTLY TOO HIGH.  WITH THE LIMITING FACTOR OF MOISTURE
AVAILABILITY...I AM COMFORTABLE WITH A NARROW WINDOW OF TIME WITH 50
POPS WEST...TO AROUND 70 EAST SUNDAY MORNING. BY AFTERNOON...THE MID
LEVELS AND LOW LEVELS RAPIDLY DRY BEHIND THE TROF. THIS SHOULD ALLOW
FOR A RAPID INCREASE IN MIXING DEPTH...AND A LATE DAY SURGE IN
TEMPERATURES IN THE WESTERN 2/3RDS. HIGHS OF UPPER 40S EAST UNDER
CLOUDS WILL GREATLY RISE TO THE MID TO UPPER 50S CENTRAL AND WEST.
WINDS OF 20 TO 25 MPH WILL BLOW FROM THE SOUTHWEST TO WEST SOUTHWEST...
WITH GUSTS TO 35 LIKELY. THE PRICE OF THIS WARM UP WILL CERTAINLY
BE PAID WITH THE STRONG WINDS.

ERVIN

.LONG TERM...(SUNDAY NIGHT THROUGH NEXT SATURDAY)
ISSUED AT 314 PM CDT SAT MAR 28 2015

SUNDAY NIGHT THROUGH TUESDAY...SFC RIDGE LOBE WILL FOLLOW EXITING
SYSTEM FOR SUNDAY NIGHT...EXPECT ENOUGH INCOMING PRESSURE GRADIENT TO
MAINTAIN WEST-NORTHWEST SFC WINDS OF 5 TO 15 MPH OVERNIGHT TO LIMIT
COLDER TEMPS THAN LOW TO MID 30S BY MONDAY MORNING. BROAD
NORTHWESTERLIES WILL STILL LOOK TO CLIPPER A WAVE OUT OF CANADA DOWN
ACRS MN BY MON EVENING...INCREASING RETURN FLOW SOUTH OF THIS
FEATURE TO MAKE FOR LATE MON AFTERNOON HIGHS IN THE UPPER 50S IN THE
FAR NORTHEASTERN CWA...TO THE MID/UPPER 60S IN THE FAR SOUTHWEST.
WITH DRY LLVL FETCH INTO THE PASSING WAVE AS IT PROPAGATES DOWN ACRS
WI MON NIGHT...FEEL THE CWA WILL BE MAINLY DRY AND PRECIP KEPT OFF TO
THE NORTHEAST ACRS THE WESTERN GRT LKS...WILL TRIM BACK SLIGHT CHC
POPS IN THE FAR NORTHEAST FOR MON EVENING. SOUTHWEST WINDS TO KEEP
TEMPS UP AT LEAST IN THE 40S MON NIGHT. FROPA OFF PASSING CLIPPER
LAT MON NIGHT INTO TUE MORNING...BUT INCOMING AIRMASS NOT ALL THAT
MUCH COLDER THAN PRE-WAVE...PLUS DEEP MIXING IN BREEZY LLVL
NORTHWEST FLOW TO BOOST TEMPS BACK CLOSE TO...IF NOT WARMER THAN
PRE-FRONTAL LATE MON AFTERNOON TEMPS.

WEDNESDAY AND THURSDAY...AS THE NEXT MAJOR L/W TROF ORGANIZES ACRS
THE ROCKIES INTO THE EASTERN PLAINS...MORE ROBUST SOUTHEAST TO
SOUTHERLY RETURN FLOW COULD PUSH MOST OF THE CWA INTO THE UPPER
60S TO 70S FOR WED HIGHS...ESPECIALLY OF PRECIP/CLOUDS ASSOCIATED WITH
AN APPROACHING FRONTAL SYSTEM HOLD OFF UNTIL WED NIGHT. 12Z GFS MORE
PROGRESSIVE WITH INCOMING FROPA WED NIGHT...WITH ASSOCIATED SHOWERS
AND THUNDERSTORMS KICKED UP BY THE PROCESS EXITING OUT OF THE CWA
BY 12Z THU MORNING. THE 12Z ECMWF STALLS THE FRONT AS IT ALIGNS MORE
PARALLEL TO WEST-SOUTHWEST STEERING FLOW LATE WED NIGHT INTO THU...
WHICH WOULD LINGER PRECIP ACRS THE CWA WELL INTO THU IF FRONT HANGS
UP ACRS THE AREA LIKE IT IS INDICATING. ADEQUATE MOISTURE RETURN
COULD PRODUCE SOME LOCALLY MODERATE TO SEASONABLY HIGH RAINFALL
TOTALS BY THU. BUT STILL SOME MODEL HANDLING ISSUES THUS LOWER
CONFIDENCE IN THIS AT THIS POINT. TEMPS A BIG CRAP SHOOT FOR THU
AT THIS POINT DEPENDING ON FRONTAL PROGRESSION AND LINGERING PRECIP
ISSUES. THE GFS SHUNTS THE BOUNDARY WELL TO THE SOUTH AS THU
PROGRESSES...WITH INCOMING RIDGING MAKING FOR A DRY BUT MUCH COOLER
FCST FOR THU AFTERNOON/NIGHT THAN THE ECMWF WOULD SUGGEST.

FRIDAY THROUGH NEXT SATURDAY...LARGE DISCREPANCIES/PHASING ISSUES
CONTINUE IN HANDLING THE MAIN UPPER WAVE ENERGY ROLLING OUT ACRS
THE MID CONUS THIS PERIOD....HOW FAR NORTH OR SOUTH THE PATHWAY IT
WILL TAKE AND WHAT TYPE OF CYCLONIC STRENGTH THE LLVL LOW PRESSURE
WILL HAVE. THE FURTHER SOUTH GFS HAS SECONDARY DEF ZONE COLD RAIN
TRANSITIONING TO A RAIN-SNOW MIX BY LATE FRI INTO FRI EVENING...
POSSIBLY TRENDING TO ALL WET SNOW WITH SOME ACCUMULATION POSSIBLE.
THE NEW EURO HAS TENDED SOUTH FROM IT/S PREVIOUS RUN...BUT MAINLY
PRODUCES A COOL SIDE DEF ZONE OF MODERATE TO LOCALLY HEAVY RAIN
FOR NEXT FRI...POSSIBLY MIXING WITH OR CHANGING OVER TO SOME WET
SNOW IN THE NORTHWEST/NORTHERN CWA FRI EVENING BEFORE EXITING. FOR
NOW...WILL KEEP MODERATE CHC POPS FOR THE END OF THE WEEK AND ALL
LIQUID STATE WITH ANY PRECIP REACHING THE SFC TO KEEP IN COMPLIANCE
WITH NEIGHBORING WFO/S.     ..12..

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 639 PM CDT SAT MAR 28 2015

VFR CONDITIONS WITH CHANGEABLE LATE MARCH WEATHER THE NEXT 24 HOURS.
SOUTH WINDS WILL INCREASE TO 10 TO 22 KTS BY LATE TONIGHT WITH BKN-
OVC MID AND HIGH CLOUDS WITH ANY CIGS AOA 7K AGL BY MORNING WITH A
FAST MOVING UPPER DISTURBANCE AND FRONT THAT IS MOISTURE STARVED.
BETWEEN 29/12 AND 29/19Z...PROB30 GROUPING FOR ELEVATED LIGHT SHOWERS
WITH ANY VISIBILITIES IN RAIN STILL AOA 4 SM AND GUSTY SOUTHWEST WINDS
OF 15 TO 25 KTS. AFTER FRONTAL PASSAGE BY LATE AFTERNOON WEST TO NORTHWEST
WINDS OF 17 TO 30 KTS AND CLEARING SKIES.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.

&&

$$

SYNOPSIS...ERVIN
SHORT TERM...ERVIN
LONG TERM...12
AVIATION...NICHOLS





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